This invention relates to heat sensors for installation in motor vehicles.
The prior art temperature measuring sensors for measuring the exhaust temperature for automotive vehicles utilized the internal resistance of the heat sensor itself to supply a signal representing the measured temperature since the conductivity of the sensor was extremely temperature-dependent. However, the disadvantage of this type of sensor was the expense involved to sense the change in conductivity of the internal resistance and the possible counter-influence of the sensor's measurement signal and the interior resistance measurement. This sometimes required an interruption of the current to insure that the correct measurement signal was being sent. Further, while it is known to include supplementary temperature probes within the measuring sensor itself and thus measure the temperature sensor with no intermediary device. It has also been found that this latter type of temperature measurement is very costly and, at present, the life expectance of the measuring sensor is much shorter than that of the temperature probes and thus the device must be replaced often.